Once the backup is created you can check the header to verify if backup was created with checksum.

RESTOREHEADERONLY

FROMDISK=N'C:\SqlAndMe.bak'

GO

Result Set:

However, if you do not have control over underlying T-SQL for backup then you can enable backup checksums using Trace Flag 3023. When this Trace Flag is turned on WITH CHECKSUM option is applied automatically for a backup.

In the following example I have run a backup before enabling Trace Flag 3023, and after enabling Trace Flag 3023 to see it’s behavior:

Now, we can look at the header of the backup file to verify if the backup has been created with checksum:

RESTOREHEADERONLY

FROMDISK=N'C:\SqlAndMe.bak'

GO

Result Set:

As we can see from the output, First backup was created without checksums and second backup (after enabling Trace Flag 3023) is created with checksums without explicitly specifying WITH CHECKSUM option.